Target-dependent polymerisation of oligonucleotides

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Solution Overview

Problem

Existing Hybridization Chain Reaction (HCR) technologies face challenges such as high background signals, irreversibility, difficulty in controlling reaction kinetics, and limited reproducibility, making them unsuitable for rapid, industrial, and routine applications.

Innovation Solution

Designing HCR oligonucleotide probes with multifunctional hairpin loops that control hybridization specificity and free energy, enabling rapid and accurate detection of target nucleic acids using kits that do not rely on toe-holding, and employing constructs with signal generating components like FRET and chemiluminescence for enhanced sensitivity and control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional HCR is used to detect target nucleic acid, then signal amplification is achieved, but background signals are high and reliability deteriorates

Engineering Contradiction:
Improvedetection accuracyVSAvoidreproducibility
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The hairpin probes are pre-designed with specific secondary structures that remain closed and inactive until triggered by the target nucleic acid. This preliminary configuration prevents background signals by ensuring probes only become active when needed, improving both detection accuracy and reproducibility

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention modifies the thermodynamic parameters of the HCR system by designing hairpin probes with specific stem-loop structures and controlling their melting temperatures. This allows precise control over probe activation thresholds, reducing background noise while maintaining signal amplification capability

Inventive Principle:
Principle #35Parameter changes

2Productivity

If traditional HCR with toe-holding is used, then signal amplification occurs, but reaction kinetics control becomes difficult and device complexity increases

Engineering Contradiction:
Improveamplification efficiencyVSAvoidreaction control complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The invention removes the toe-holding element from the traditional HCR mechanism, simplifying the probe design to essential hairpin structures. This extraction eliminates the complexity of controlling toe-holding initiation while preserving the core signal amplification functionality through target-triggered hairpin opening

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The hairpin probes automatically regulate their own activation through target-dependent conformational changes. The probes self-assemble and self-regulate the reaction kinetics without requiring external control mechanisms, simplifying the overall system while maintaining amplification efficiency

Inventive Principle:
Principle #25Self-service

3Productivity

If rapid detection is implemented with shortened hybridization time, then productivity improves, but measurement precision may deteriorate

Engineering Contradiction:
Improvedetection speedVSAvoidhybridization accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The hairpin probe structure creates a curved, pre-organized configuration that positions the binding region optimally for target interaction. This structural curvature facilitates rapid hybridization by reducing the entropic penalty of binding, enabling fast detection without sacrificing accuracy

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The probes are pre-configured in closed hairpin states with binding regions sequestered and ready for rapid activation. This preliminary organization allows immediate target binding upon encounter, achieving both speed and precision without requiring extended hybridization times

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution provides rapid, accurate, and reproducible nucleic acid detection within two hours, preferably under one hour, with hybridization times as short as 30 minutes, suitable for automation and multiplexing, and applicable to various sample types.

Implementation Method 1

on binding of the target nucleic acid to the Target Initiation probe the stem region of the Target Initiation probe opens and permits hybridisation to the loop region of the first Chain Loop probe

Methodology Applied
Scientific EffectHybridization:

Implementation Method 2

triggers a cascade reaction of subsequent hybridisations, more precisely, a cascade of toehold-mediated strand displacements, leading to the formation of a long nicked double-stranded DNA

Methodology Applied
Scientific EffectToehold-mediated strand displacement:

Implementation Method 3

signal generating components like FRET and chemiluminescence for enhanced sensitivity

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Implementation Method 4

signal generating components like FRET and chemiluminescence for enhanced sensitivity

Methodology Applied
Scientific EffectChemiluminescence: Chemiluminescence

Data Source

PatentEP4281584B1Target-dependent polymerisation of oligonucleotides
Publication Date: 2026.04.08 QBIOTIX LTD
  • EP4281584B1 patent drawingFigure 1
  • EP4281584B1 patent drawingFigure 2
  • EP4281584B1 patent drawingFigure 3

AI summary

The present invention provides kits and methods for the rapid and sensitive detection of a target nucleic acid through target initiated polymerisation.